Example for AlterColumn?

[kalafut]

Hi! Thanks for Clear which is working great.

I'm struggling to use change_column_type or even directly AlterColumn in a migration. I continue to get:

In lib/clear/src/clear/migration/operation/columns.cr:73:28

 73 | def initialize(@table, @column_name, column_type, new_column_name, new_column_type)
                             ^-----------
Error: can't infer the type of instance variable '@column_name' of Clear::Migration::AlterColumn

Do you have an example of its use? In the mean time I will write SQL.